The present invention relates to a lubricant for engines, in particular diesel and natural gas powered internal combustion engines.
Lubricant compositions such as crankcase motor oils have been the subject of much research to improve their physical and chemical properties. For instance, research has been directed to providing so-called ashless lubricants, that is, those which do not contain metals which form sulfated ash under the ASTM test D-784. Ashless lubricants would have the advantage of reducing combustion chamber deposits. But to prepare such a material which passes rigid performance tests has been difficult, since metal salts in the form of detergents have long been key components in engine oils. It is also desirable to minimize the amount of phosphorus in lubricants. Although phosphorus does not contribute to sulfated ash, it can lead to poisoning of catalysts in pollution control devices such as emission catalysts or traps when amounts of phosphorus make their way into the exhaust system. Nevertheless, many conventional antiwear additives contain phosphorus, so its total removal has presented a challenge. The present invention, however, provides an ashless, zero phosphorus or low phosphorus lubricant composition which is suitable for lubricating diesel and natural gas powered engines.
Doner et al. U.S. Pat. No. 4,582,617, Apr. 15, 1986, discloses grease compositions including a boronated epoxide (d), metal or non-metal phosphates, and a metal (or amine) hydroxy-containing soap grease thickener. Antioxidants are also disclosed.
Small, Jr. U.S. Pat. No. 4,629,576, Dec. 16, 1986, discloses engine lubricating oil containing (a) alkyl succinimide, and (d) a borated long chain 1,2 alkane diols. Other additives may be present to obtain a proper balance of properties such as dispersion and oxidation. Preferably the lubricant composition also contains neutral or over-based salts.
Horodysky U.S. Pat. No. Re. 32,246, Sep. 9, 1986, discloses lubricants containing borated epoxides. Other materials can be present including coantioxidants. Metal salts can also be present.
Wirth et al. U.S. Pat. No. 4,689,162, Aug. 25, 1987, discloses boron-containing compounds as additives for lubricants. Dispersants and antioxidants can also be present.